1. Field of the Invention
The present invention relates to a switch mechanism for use, for example, in an electrophotographic image forming apparatus such as a copier, a facsimile, a printer, and so on, and in particular, relates to a switch mechanism capable of reliably detecting an opening/closing status of a cover attached to a body of the electrophotographic image forming apparatus.
2. Discussion of the Related Art
A switch mechanism is generally utilized for detecting an opening/closing status of a cover attached to a body of the image forming apparatus. A conventional switch mechanism includes a so-called limit switch disposed in the body of the image forming apparatus, and an activating member for activating the limit switch, which is mounted on the body cover at a portion corresponding to the limit switch. The activating member generally activates the limit switch when the body cover is closed, and deactivates the same when the body cover is opened.
The activating member generally has a lever whose one end is connected with the body cover and another end which extends to an actuator of the limit switch to push. The body cover generally includes a large-sized plane plate made of plastic using a molding process. Thus, the body cover is weak in strength, and thereby tends to bend. Therefore, a leading end of the activating member hardly faces the limit switch accurately when the body cover is closed. Further, an operative distance of the limit switch is generally very small, i.e. about a few millimeters. Thus, the limit switch of the conventional switch mechanism sometimes erroneously operates.
Further, the activating member may interrupt maintenance because the activating member generally extends from the body when the body cover is opened. Further, the activating member may be damaged due to physical contact by an operator during the maintenance.
To avoid such an erroneous operation of the limit switch, parts of the switch mechanism are highly precisely manufactured. However, it generally costs very much.
Further, as described in Japanese Laid-Open Patent Application No. 8-285183, to avoid the above-mentioned problems, a guide member is disposed between a body cover and a switch to guide an activating member to the switch. Also, a folding mechanism is employed beside the guide member and is linked with the body cover. The activating member is folded by the folding mechanism to hide in a hollow portion of the body cover when the body cover is opened.
However, such a conventional switch mechanism does not always enable the activating member to activate the limit switch because a leading end of the activating member, which is required to reach the limit switch, sometimes varies its stopping position when the body cover is closed due to a nonpositional limitation of the activating member in its moving direction. As a result, the leading end sometimes does not reach the limit switch and accordingly the limit switch may erroneously operate due to an insufficient contact of the leading end. Thus, the guiding member does not determine the deepest position of the leading end.
Further, since the folding mechanism is separately employed from the switch mechanism, a construction of the image forming apparatus is complex.